Torque spanners

ABSTRACT

A torque spanner comprises: a body having a tubular passageway therethrough; a first lever pivoted within the passageway intermediate its ends, one of its ends projecting from the passageway which end is arranged to apply torque or carry torque applying means of which the torque reaction tends to rotate the lever about its pivot; a bell-crank lever within the passageway, one arm of the bell-crank lever being pivotally connected to the other arm of the first lever, the fulcrum of the bell-crank lever abutting the wall of the passageway for rocking and sliding or rolling movement thereon; and spring means acting on the other arm of the bell-crank lever to bias the bell-crank lever into one position, the arrangement being such that application of a preset torque to the said one end of the first lever causes the first lever to rotate and pivot the bell-crank lever out of its one position against the action of the spring means, and thus causes part of the bell-crank lever, or a striker connected thereto, to strike the wall of the passageway to give an audible indication that the preset toreque has been reached.

[22] Filed:

United States Patent 1191 Krain 1111 3,742,786 July3,1973

[ TORQUE SPANNERS [75] Inventor: Harry Wolfgang Krain, Reading,

England May 24, 1971 211 App]. No.: 146,101

3,355,970 l2/l967 Kundsen et al. 8l/52.4

Primary Examiner-Robert C, Riordon Assistant Examiner-Roscoe V. ParkerAttorney-Bacon & Thomas r ml l [57] ABSTRACT A torque spanner comprises:a body having a tubular passageway therethrough; a first lever pivotedwithin the passageway intermediate its ends, one of its ends projectingfrom the passageway which end is arranged to apply torque or carrytorque applying means of which the torque reaction tends to rotate thelever about its pivot; a bell-crank lever within the passageway, one armof the bell-crank lever being pivotally connected to the other arm ofthe first lever, the fulcrum of the bell-crank lever abutting the wallof the passageway for rocking and sliding or rolling movement thereon;and spring means acting on the other arm of the bell-crank lever to biasthe bell-crank lever into one position, the arrangement being such thatapplication of a preset torque to the said one end of the first levercauses the first lever to rotate and pivot the bell-crank lever out ofits one position against the action of the spring means, and thus causespart of the bell-crank lever, or a striker connected thereto, to

strike the wall of the passageway to give an audible indication that thepreset toreque has been reached.

7 Claims, 4 Drawing Figures llllw SHEEI 1 0f 2 w/MM PATENTEDJUL 3 I973plunger 17 and adjusting nut 9.

TORQUE SPANNERS The invention relates to torque spanners.

The invention provides a torque spanner which is adapted to give anaudible indication that the preset torque has been reached.

It is preferred that the spring means are arrangeable to apply a presetload to the bell-crank lever, the bellcrank lever transmitting load tothe first lever, the first lever, when the torque applied at the saidone end is zero, being prevented from moving under the action of theload by a reaction between the first lever and the wall of thepassageway so that torque applied to the first lever does not rotate thefirst lever away from the wall of the passageway to pivot the bell-cranklever until the applied torque imparts to the first lever a moment aboutits pivot greater than the moment imparted by the said reaction.

It is further preferred that the positions of the bellcrank lever andspring means are such that as the first lever begins to move the loadtransmitted to the first lever by the bell-crank lever reduces so thatthe first lever accelerates.

Preferably the spring means act on the said other arm of the bell-cranklever via a compression link pivotally connected to the said other arm.The spring means may comprise a plunger pivotably connected to the linkand slidable (e.g. by means of its material properties or on rollers orballs) within the passageway and a coil spring on the side of theplunger remote from the levers one end of the spring acting against theplunger and the other end acting against an abutment on the body.

It is preferred that the link is arranged such that when the bell-cranklever is in the said one position the link extends along the passagewayand is inclined to the axis of the passageway, and when the bell-cranklever pivots out of its said one position the link is caused to pivotinto a position in which it lies substantially parallel to the axis ofthe passageway.

The link may be provided with a projection to serve as the striker.

Preferably the abutment on the body is movable -along the passageway sothat the compression of the spring may be varied to adjust the presettorque.

The fulcrum of the bell-crank lever may be provided with a roller.

Preferably the spanner automatically resets when the spanner is relievedof torque greater than or equal to the preset torque.

By way of example, a specific embodiment of the invention will now bedescribed with reference to the accompanying drawings, in which:

FIG. 1 is a section through a torque spanner according to the inventionunder no load;

FIG. 2 is a part section through the torque spanner of FIG. 1 thepre-set torque having been applied;

FIG. 3 is a side section of the torque spanner of FIG. 1; and

FIG. 4 is a section through an alternative spanner head.

The spanner comprises a tubular body 10, a first bell-crank lever at 16,a plunger 17 pivoted to the link.

15 at 18, an end cap 19, an adjusting screw 7, an adjusting nut 9, and acompression spring 20 lying betwee The lever 11 carries in a socket atone end a square 21 which extends in a direction parallel to the axis ofpivot 12. The square has two ball cathces 22 and isarranged to receiveany one ofa number of torque applying heads such as wrench sockets.

The bell-crank lever 13 has at its fulcrum a roller 23 abutting theinternal wall of tube 10. Thus the lever 13 pivots about its fulcrum byrocking on the tube wall.

The link 15 has an obliquely projecting end 24 to serve as a striker.

As best seen in FIG. 3 adjusting nut 9 is screwed onto the adjustingscrew 7, and the action of spring 20 tends to urge the nut and screw tothe right of the Figure. A circlip 8 engaging a groove in the internalwall of tube 10 holds the screw 7 in position. A cylindrical socket inone end of screw 7 engages a cylindrical extension of plunger 17 forcentring purposes. The other end of screw 7 has a square sectionprojection 6 which engages a square socket in cap 19. The cap 19 isfixed to the screw 7 by a flat-head screw, and nut 9 is keyed to thetube 10 to prevent the nut from rotating. Thus the screw is rotatablewith the cap 19 and rotation of the cap 19 therefore causes nut 9 tomove along tube 10, thus varying the degree of compression in spring 20.i

In use the spanner parts are arranged in the stable state shown inFIG. 1. The spring 20 acting on plunger 17 holds the parts in position.A desired torque is set by adjusting cap 19 to apply a suitablecompression to the spring. A pointer associated with the adjusting nut 9indicates on a scale the torque which corresponds to any given positionof the cap.

Once the desired torque has been set, the spanner may be used to applytorque to, for example, nuts, bolts, bottle caps, valves, plasticcomponents etc. As torque is applied, an equal and opposite torque isapplied to the lever 10. When the torque reaches the preset value lever11 pivots anti-clockwise as viewed in FIGS. 1 and 2, lever 13 pivotsclockwise, rolling slightly to the right along the tube, and link 15urges the plunger and spring to the right, the parts taking up theposition shown in FIG. 2. Link 15 operates with a toggle action andmoves with increasing acceleration until projection 24 strikes the tubewall bringing the parts to rest and indicating audibly that the presettorque has been applied. In this position application of furtherforcewill cause the spanner to act as a conventional spanner.

Link 15 is of such dimensions that in the position shown in FIG. 2 pivot16 lies below a line joining pivot 18 and fulcrum 23. Thus when thespanner is relieved of torque the spring 20 causes the parts to returnto the position shown in FIG. 1. Thus the spanner automatically resets.

Furthermore the relative dimensions of the levers 11-,

13 and the link 15, and the positioning of the pivots,

torque the movement of the lever 11 is considerably less than that oflink 15. Thus the amount of rotational movement of the spanner betweenapplication of the preset torque and the spanner reaching the positionshown in FIG. 2 is very small. Consequently the spanner cannot pick upmuch speed after application of the preset torque before it begins toact as a conventional spanner. This reduces the possibility thatsubstantial additional torque will be accidentally applied in additionto the preset torque when the spring yields.

FIG. 4 shows an alternative head with which lever 11 may be provided.Instead of a square 21 carried in a square hole the head comprises aratchet mounted square 28. The square has a ball-catch 29 for theattachment of torque applying means.

I claim:

1. A torque spanner comprising: a body having a tubular passagewaytherethrough; a first lever pivoted within the passageway intermediateits ends, one of its ends projecting from the passageway which end isarranged to apply torque or carry torque applying means of which thetorque reaction tends to rotate the lever about its pivot; a bell-cranklever within the passageway, one arm of the bell-crank lever beingpivotally connected to the other end of the first lever, the fulcrum ofthe bell-crank lever abutting the wall of the passageway for rocking andsliding movement thereon;

a striker connected to the bell-crank lever; and spring means acting onthe other arm of the bell-crank lever to bias the bell-crank lever intoone position, the arrangement being such that application of a presettorque to the said one end of the first lever causes the first lever torotate and pivot the bell-crank lever out of its one position againstthe action of the spring means, and thus cause the striker to strike thewall of the passageway to give an audible indication that the presettorque has been reached.

2. A torque spanner as claimed in claim 1 in which the spring means arearrangeable to apply a preset load to the bell-crank lever, thebell-crank lever transmitting load to the first lever, the first lever,when the torque applied at the said one end is zero, being preventedfrom moving under the action of the load by a reaction between the firstlever and the wall of the passageway so thattorque applied to the firstlever does not rotate the first lever away from the wall of thepassageway to pivot the bell-crank lever until the applied torqueimparts to the first lever a moment about its pivot greater than themoment imparted by the said reaction.

3. A torque spanner as claimed in claim 2 in which the positions of thebell-crank lever and spring means are such that as the first leverbegins to move the load transmitted to the first lever by the bell-cranklever reduces so that the first lever accelerates.

4. A torque spanner as claimed in claim 1 in which the spring means acton the said other arm of the bellcrank lever via a compression linkpivotally connected to the said other arm.

5. A torque spanner as claimed in claim 4 in which the spring meanscomprise a plunger pivotably connected to the link and slidable withinthe passageway and a coil spring on the side of the plunger remote fromthe levers one end of the spring acting against the plunger and theother end acting against an abutment on the body.

6. A torque spanner as claimed in claim 4 in which the link is arrangedsuch that when the bell-crank lever is in the said one position the linkextends along the passageway and is inclined to the axis of thepassageway, and when the bell-crank lever pivots out of its said oneposition the link is caused to pivot into a position in which it liessubstantially parallel to the axis of the passageway.

7. A torque spanner as claimed in claim 4 in which the link is providedwith a projection to serve as the striker.

UNITED STATES PATENT OFFICE- CERTIFICATE OF CORRECTION Patent No.3,742,785 Dated 1111;; 2 197 n ks HARRY WOLFGANG KRAIN It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

At'page 1, column 2, line 49, change "below" to -aboveand line 50,change "fulcrum 23" to pivot 14 Signed and sealed this 9th day of July1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents PO-105O (10-69) USCOMM-DC 60376-P69 u.s. GOVERNMENT Pmm'mcOFFICE: I909 0-366-334

1. A torque spanner comprising: a body having a tubular passagewaytherethrough; a first lever pivoted within the passageway intermediateits ends, one of its ends projecting from the passageway which end isarranged to apply torque or carry torque applying means of which thetorque reaction tends to rotate the lever about its pivot; a bell-cranklever within the passageway, one arm of the bell-crank lever beingpivotally connected to the other end of the first lever, the fulcrum ofthe bell-crank lever abutting the wall of the passageway for rocking andsliding movement thereon; a striker connected to the bellcrank lever;and spring means acting on the other arm of the bell-crank lever to biasthe bell-crank lever into one position, the arrangement being such thatapplication of a preset torque to the said one end of the first levercauses the first lever to rotate and pivot the bell-crank lever out ofits one position against the action of the spring means, and thus causethe striker to strike the wall of the passageway to give an audibleindication that the preset torque has been reached.
 2. A torque spanneras claimed in claim 1 in which the spring means are arrangeable to applya preset load to the bell-crank lever, the bell-crank lever transmittingload to the first lever, the first lever, when the torque applied at thesaid one end is zero, being prevented from moving under the action ofthe load by a reaction between the first lever and the wall of thepassageway so that torque applied to the first lever does not rotate thefirst lever away from the wall of the passageway to pivot the bell-cranklever until the applied torque imparts to the first lever a moment aboutits pivot greater than the moment imparted by the said reaction.
 3. Atorque spanner as claimed in claim 2 in which the positions of thebell-crank lever and spring means are such that as the first leverbegins to move the load transmitted to the first lever by the bell-cranklever reduces so that the first lever accelerates.
 4. A torque spanneras claimed in claim 1 in which the spring means act on the said otherarm of the bell-crank lever via a compression link pivotally connectedto the said other arm.
 5. A torque spanner as claimed in claim 4 inwhich the spring means comprise a plunger pivotably connected to thelink and slidable within the passageway and a coil spring on the side ofthe plunger remote from the levers one end of the spring acting againstthe plunger and the other end acting against an abutment on the body. 6.A torque spanner as claimed in claim 4 in which the link is arrangedsuch that when the bell-crank lever is in the said one position the linkextends along the passageway and is inclined to the axis of thepassageway, and when the bell-crank lever pivots out of its said oneposition the link is caused to pivot into a position in which it liessubstantially parallel to the axis of the passageway.
 7. A torquespanner as claimed in claim 4 in which the link is provided with aprojection to serve as the striker.